1. Field of Invention
This invention relates generally to biofeedback, and more particularly to a biofeedback therapy system in which an individual, while one of his involuntary physiologic functions is being monitored, is intermittently subjected during a training run to stress-inducing stimuli in a manner making it possible for the individual mentally to regulate the function being monitored.
2. Status of the Art
An individual's ability to mentally control certain of his physiological functions such as body temperature or blood pressure is known as self-regulation. For hundreds of years in the Far East, Yogis and Zen Buddhists have practiced the art of self-regulation.
But with the exception of those committed to transcendental meditation, self-regulation techniques have not been widely practiced in Western society, possibly because many disorders induced or aggravated by stress which lend themselves to alleviation by self-regulation can more readily be treated by medication. Thus a muscle contraction or tension headache as well as migraine, a vascular headache that is more painful than a tension headache, can, to some degree, be relieved by aspirin and other drugs. Such medication does not do away with stress factors responsible for the headache but serves only to moderate the symptoms. Moreover, aspirin and other drugs, when taken frequently and in large doses, often have deleterious side effects.
In recent years, biofeedback techniques have been developed which represent a more effective form of self-regulation. In biofeedback, an involuntary or unconscious physiologic process, such as the heart beat or the brain wave, is made perceptible to the senses, thereby making it possible for the individual to manipulate the process by conscious mental control.
Stress is expressed in many ways, and may be manifested by a headache or by high blood pressure. Of overriding importance in stress therapy is learning to relax and thereby reduce tension and its physiological consequences. With biofeedback, one is able to achieve mental and physical relaxation by being fed back information regarding an unconscious physiological process. This information is derived by means of a non-invasive sensor which measures peripheral skin temperature or skin resistance, heart rate, blood pressure, pulse rate, and some other process variables.
Thus a signal from an electromyograph is indicative of varying levels of muscular activity; the higher the signal amplitude, the greater the amount of muscular tension. A high level of muscular tension reflects a high degree of stress, giving rise to tension headaches, facial pain and tics, and other stress-related illnesses. By means of biofeedback, one can monitor a specific physiologic process and derive therefrom a visible or audible signal indicative of the process. In this way, the user can manipulate the process being monitored by learning to control the signal it yields. By biofeedback one can reduce muscle tension, slow down a rapid heart rate, regulate blood flow to alleviate circulatory problems and, in general, relax the nervous system.
The efficacy of biofeedback is well established. Thus, in the article by Sidney Leber, M.D., "Biofeedback in Clinical Psychiatric Practice" appearing in Psychiatric Opinion of October 1979, the author states that patients previously dependent on medication for migraine and other stress-related conditions which are responsive to feedback "can reduce their medications to a line of last defense rather than continue to routinely ingest medications as a way of life".
Biofeedback systems which are commercially available come in varying degrees of complexity and sophistication. Thus, Excelsior & Co. of Agoura, Calif., markets a stress control card that measures stress by means of a temperature-sensitive patch that changes color--a red color being indicative of tension, green representing a state of calm, and blue a relaxed state. Printed on the back of the card are mental relaxation techniques.
In order to teach relaxation and stress management techniques, New Frontier, Inc. markets a kit that includes a biofeedback unit manufactured by Farall Instruments, Inc. of Grand Island, Nebr. This unit is provided with an array of color-coded LEDs to provide a visible readout as well as audio feedback. The kit also includes audio relaxation tapes and a training manual.
Thought Technology Ltd., of Montreal, Canada, markets a portable biofeedback system that monitors muscle tension, skin resistance or skin temperature through a headset operating in conjunction with a headband monitor having electrodes therein which engage the forehead.
Lafayette Instrument Company of Lafayette, Ind., offers a biofeedback system which teaches tension control and relaxation, use being made of fingertip electrodes for GSR feedback and a thermistor sensor for temperature feedback. The system also includes an instructional cassette tape.
The difficulty experienced with existing biofeedback systems is that they require a fairly long training period before the user can obtain beneficial effects. The reason for this is that internal stress conditions are not a constant; and when the user first turns on his unit, he may then be in a fairly relaxed state. The unit therefore lacks, as it were, a primer; for unless the user is in a state of stress, he has nothing to work against for purposes of stress management.
Also, existing units do not mark the exact level of stress at the time the unit is first turned on to provide a set point to which the user can refer in determining the extent to which he is able, in the course of a training run, to regulate his stress.
A more serious drawback of existing feedback monitors is that their readout provides only a rough or very general indication of the prevailing state of stress. Thus where the readout is in the form of color-coded indications, such as blue for a relaxed state, yellow for low stress, and red for high stress, this read-out is imprecise. There are various levels of stress, and a red color high-stress indication, for example, does not tell the viewer whether the level of high stress is at the bottom or top of the high stress range or at some intermediate level.
Thus in a training run, the user may succeed in somewhat reducing stress, but to a degree insufficient to cause the color indicator to step from red to yellow. Hence the user will not be informed of his partial success, and this will discourage him from continuing the practice of feedback therapy. Where the feedback is in the form of an audible signal of varying pitch or loudness, this too affords an imprecise indication of stress level.